This research aims to improve our understanding of sperm maturation, the process in the epididymis whereby immature sperm cells achieve the competency to later undergo capacitation and fertilization. The research will focus on the final events that are critical in acquisition by sperm of mature status. An extension of presently useful methodology for assessment of functional sperm maturation will encompass various modifications of organ culture under steroidal influences, in vitro capacitation and in vitro fertilization. Emphasis will be on linking steroids with epididymal proteins that can directly effect maturation of immature sperm cells. The work will include detailed light and electron microscopic studies. Attention will be paid to changes in motility and longevity as well to fertilizing ability. Identification of essential components of the pathway to maturation will be followed-up by immunological and chemical approaches toward control.